All flights from Tampa International Airport have been canceled Tuesday as Hurricane Idalia barrels toward the Florida's Gulf Coast.

So far, that's the only major airport significantly affected by the storm, which strengthened into a hurricane with maximum sustained winds of 75 mph overnight. The St. Pete-Clearwater International Airport Terminal building also is closing Tuesday afternoon.

Flight tracking website FlightAware shows that theSouthwest Airlines schedule is the most affected, with 143 cancellations. United, Delta and American Airlines are also impacted with about 150 delays combined and nearly 200 cancellations.

Several airlines, including Delta, Southwest, JetBlue and United, have issued advisories to passengers traveling to airports in Idalia's path, allowing passengers to make changes for free within an allotted time. United also added additional flights from Orlando and Sarasota to its hubs to help people leave the area.

Idalia is expected to intensify considerably to a powerful Category 3 strength before making landfall Wednesday in Florida, the National Hurricane Center said.

Evacuations have begun and the National Guard is on call as the storm could deliver a devastating blow to parts of Florida's Gulf Coast, with life-threatening storm surge and damaging winds. It is expected to make landfall well north of Tampa, in Florida's Big Bend region — but a small shift in the track could put the vulnerable population center more at risk.